Aluminate fluorescent material, light emitting device using the same, and method of producing aluminate fluorescent material

ABSTRACT

Provided is an aluminate fluorescent material having a high emission intensity and having a composition containing a first element that contains one or more of Ba and Sr, and a second element that contains Mg and Mn. In the composition, when a molar ratio of Al is 10, a total molar ratio of the first element is a parameter a, a total molar ratio of the second element is a parameter b, a molar ratio of Sr is a product of a parameter m and the parameter a, a molar ratio of Mn is a product of a parameter n and the parameter b. The parameters a and b satisfy 0.5&lt;b&lt;a≤0.5b+0.5&lt;1.0, the parameter m satisfies 0≤m≤1.0, and the parameter n satisfies 0.4≤n≤0.7.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of U.S. patent application Ser. No.15/615,896, filed Jun. 7, 2017, now U.S. Pat. No. 10,208,247 issued onFeb. 19, 2019, which claims the benefit of Japanese Patent ApplicationNo. 2016-115062, filed on Jun. 9, 2016, and Japanese Patent ApplicationNo. 2017-054756, filed on Mar. 21, 2017, the disclosures of which arehereby incorporated by reference in their entirety.

BACKGROUND Technical Field

The present invention relates to an aluminate fluorescent material, alight emitting device using the same, and a method of producing analuminate fluorescent material.

Description of Related Art

Various light emitting devices that emit white light, bulb color light,orange light by combination of a light emitting diode (LED) and afluorescent material have been developed. In these light emittingdevices, a desired luminescent color can be obtained according to theprinciple of light color mixing. As a light emitting device that emitswhite light, a light emitting device using a light emitting element thatemits blue color and a fluorescent material that emits yellow color iswell known. The light emitting device using a light emitting elementthat emits blue color and a fluorescent material that emits yellow coloror the like is desired to be used in a wide range of fields of generallighting, in-car lighting, displays, backlights for liquid crystals,etc. Among these, the fluorescent material for use in a light emittingdevice for backlights for liquid crystals is required to have a highcolor purity in addition to a high emission efficiency for reproducingcolors in a broad range on the chromaticity coordinate system. Inparticular, the fluorescent material for use in a light emitting devicefor backlights for liquid crystals is desired to have a narrow fullwidth at a half maximum (FWHM—hereinafter this is referred to as “halfvalue width”) of the emission peak in the emission spectrum thereof andto have a high color purity, from the viewpoint of realizing a broadcolor reproducibility range.

Japanese Unexamined Patent Publication No. 2004-155907 discloses amanganese-activated aluminate fluorescent material such as (Ba,Sr)MgAl₁₀O₁₇:Mn²⁺ as a green emitting fluorescent material having anarrow half value width of the emission peak in the emission spectrumthereof. The manganese-activated aluminate fluorescent materialdisclosed in Japanese Unexamined Patent publication No. 2004-155907 is afluorescent material that emits light when excited with vacuum UV rayshaving a wavelength in a range of 10 nm to 190 nm, specifically vacuumUV ray at 146 nm.

SUMMARY

However, the manganese-activated aluminate fluorescent materialdisclosed in Japanese Unexamined Patent Publication No. 2004-155907 is,when combined with a light emitting element that emits light having anemission peak wavelength in a range of 380 nm or more and 485 nm or less(hereinafter this may be referred to as “near-UV to blue region”),insufficient in emission intensity.

Consequently, an object of the present invention is to provide analuminate fluorescent material capable of having a high emissionintensity through photoexcitation in a near-UV to blue region, a lightemitting device, and a method for producing an aluminate fluorescentmaterial.

For solving the above-mentioned problem, the present disclosure includesthe following aspects.

A first embodiment of the present disclosure relate to an aluminatefluorescent material having a composition containing a first elementthat contains one or more elements selected from Ba and Sr, and a secondelement that contains Mg and Mn, wherein in the composition of thealuminate fluorescent material, when a molar ratio of Al is taken as 10,a total molar ratio of the first element is a value of a parameter a, atotal molar ratio of the second element is a value of a parameter b, amolar ratio of Sr is a product of a value of a parameter m and the valueof the parameter a, a molar ratio of Mn is a product of a value of aparameter n and the value of the parameter b, the values of theparameters a and b satisfy the following requirement (1), the value ofthe parameter m satisfies the following requirement (2), and the valueof the parameter n satisfies the following requirement (3):0.5<b<a≤0.5b+0.5<1.0  (1),0≤m≤1.0  (2), and0.4≤n≤0.7  (3).

A second embodiment of the present disclosure relates to a lightemitting device including the aluminate fluorescent material and anexcitation light source.

A third embodiment of the present disclosure relate to a method ofproducing an aluminate fluorescent material, which includes mixing andheat-treating compounds that contain elements so as to provide acomposition containing a first element that contains one or moreelements selected from Ba and Sr, a second element that contains Mg andMn, and Al and O, wherein in the composition, when a molar ratio of Alis taken as 10, a total molar ratio of the first element (Ba, Sr) is avalue of a parameter a, a total molar ratio of the second element (Mgand Mn) is a value of a parameter b, a molar ratio of Sr is a product ofa value of a parameter m and the value of the parameter a, a molar ratioof Mn is a product of a value of a parameter n and the value of theparameter b, the values of the parameters a and b satisfy the followingrequirement (1), the value of the parameter m satisfies the followingrequirement (2), and the value of the parameter n satisfies thefollowing requirement (3):0.5<b<a≤0.5b+0.5<1.0  (1),0≤m≤1.0  (2), and0.4≤n≤0.7  (3).

In accordance with embodiments of the present disclosure, it is possibleto provide an aluminate fluorescent material having a high emissionintensity through excitation by light having an emission spectrum in arange of 380 nm or more and 485 nm or less, a light emitting deviceusing the same, and a method of producing an aluminate fluorescentmaterial.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic cross-sectional view showing one example of alight emitting device, according to an embodiment of the presentdisclosure.

FIG. 2 is a diagram showing light emission spectra of the aluminatefluorescent materials according to an example of an embodiment of thepresent disclosure and a comparative example.

FIG. 3 is a diagram showing reflection spectra of the aluminatefluorescent materials according to the example of an embodiment of thepresent disclosure and the comparative example.

DETAILED DESCRIPTION

The aluminate fluorescent material, the light emitting device, and theproduction method for an aluminate fluorescent material of the presentinvention are described on a basis of the embodiments and examples. Theembodiments shown below are exemplifications for exemplifying thetechnical idea of the present invention, and the present invention isnot limited to the aluminate material, the light emitting device and theproduction method for an aluminate fluorescent material described below.The relationship between the color name and the chromaticity coordinate,and the relationship between the wavelength range of light and the colorname of monochromatic light in accordance with JIS Z8110.

Aluminate Fluorescent Material

The aluminate fluorescent material of the first aspect of the presentinvention is an aluminate fluorescent material having a compositioncontaining a first element that contains one or more elements selectedfrom Ba and Sr, and a second element that contains Mg and Mn, wherein inthe composition of the aluminate fluorescent material, when a molarratio of Al is taken as 10, a total molar ratio of the first element isa value of a parameter a, a total molar ratio of the second element is avalue of a parameter b, a molar ratio of Sr is a product of a value of aparameter m and the value of the parameter a, a molar ratio of Mn is aproduct of a value of a parameter n and the value of the parameter b,the values of the parameters a and b satisfy the following requirement(1), the value of the parameter m satisfies the following requirement(2), and the value of the parameter n satisfies the followingrequirement (3):0.5<b<a≤0.5b+0.5<1.0  (1),0≤m≤1.0  (2), and0.4≤n≤0.7  (3).

In the composition of the aluminate fluorescent material, the value ofthe parameter a is a total molar ratio of Ba and Sr. In the compositionof the aluminate fluorescent material, when the value of the parameter ais not a value satisfying the requirement (1), the crystal structure maybe unstable and the emission intensity may lower. In the composition ofthe aluminate fluorescent material, the value of the parameter b is atotal molar ratio of Mg and Mn. In the composition of the aluminatefluorescent material, when the value of the parameter b is 0.5 or less,the crystal structure may be unstable and the emission intensity maylower.

In the composition of the aluminate fluorescent material, the value ofthe parameter a and the value of the parameter b are preferably valuessatisfying the following requirement (4).0.7<b<a≤0.5b+0.5<1.0  (4)

In the composition of the aluminate fluorescent material, when the valueof the parameter b is a value of more than 0.7, the crystal structure ofthe aluminate fluorescent material can be stabilized more and theemission intensity of the aluminate fluorescent material can be higher.

In the composition of the aluminate fluorescent material, the value ofthe parameter m indicates the molar ratio of Sr when the total molarratio of Ba and Sr of the first element is 1, and the first element maybe all Ba or may be all Sr.

In the composition of the aluminate fluorescent material, the value ofthe parameter n indicates the molar ratio of Mn when the total molarratio of Mg and Mn of the second element is 1. In the composition of thealuminate fluorescent material, when the value of the parameter nindicating the molar ratio of Mn among Mg and Mn of the second elementis less than 0.4 or more than 0.7, the emission intensity throughphotoexcitation in a near UV to blue region may lower.

In the composition of the aluminate fluorescent material, the value ofthe parameter n is preferably a value satisfying a requirement of0.4≤n≤0.6.

In the composition of the aluminate fluorescent material, when the valueof the parameter n is the value satisfying the requirement of 0.4≤n≤0.6,the emission intensity may be increased more and the emission intensityof the aluminate fluorescent material through photoexcitation in a nearUV to blue region can be higher.

In the composition of the aluminate fluorescent material, the product ofthe value of the parameter n indicating the molar ratio of Mn in thecomposition and the value of the parameter b (b×n) is preferably a valuesatisfying a requirement of 0.3<b×n<0.6.

For example, it is considered that the reason why the emission intensitythrough photoexcitation in a near-UV to blue region of themanganese-activated aluminate fluorescent material disclosed in JapaneseUnexamined Patent Publication No. 2004-155907 is low would be because,as the emission characteristics of the fluorescent material, theabsorbance of light in a near-UV to blue region is lower than theabsorbance of vacuum UV rays. The aluminate fluorescent material of thefirst embodiment of the present disclosure is, when excited with lightin a near-UV to blue region, able to absorb a larger amount of light ina near-UV to blue region and therefore can have an increased emissionintensity since the activation amount by Mn is larger than theabove-mentioned predetermined value. In addition, by reducing the Mnactivation amount to be lower than the above-mentioned predeterminedvalue, concentration quenching to be caused by too much activation couldbe prevented and therefore the emission intensity can be therebyincreased.

Preferably, the aluminate fluorescent material has a compositionrepresented by the following formula (I). The aluminate fluorescentmaterial having a composition represented by the formula (I) has a highemission intensity and through photoexcitation in a near-UV to blueregion, the emission intensity thereof can be higher.(Ba_(1−m),Sr_(m))_(a)(Mg_(1−n),Mn_(n))_(b)Al₁₀O_(15+a+b)  (I)wherein, a, b, m and n each are a number satisfying0.5<b<a≤0.5b+0.5<1.0, 0≤m≤1.0, and 0.4≤n≤0.7.

Regarding the aluminate fluorescent material of the first embodiment ofthe present disclosure, the half value width of the emission peak in theemission spectrum thereof, as excited with light in a near-UV to blueregion, for example, with light having an emission peak wavelength of450 nm, is preferably 45 nm or less, more preferably 40 nm or less, evenmore preferably 30 nm or less. As a fluorescent material capable ofemitting green light by photoexcitation in a near-UV to blue region, forexample, there is known a β-sialon fluorescent material excited byeuropium (Eu). The half value width of the emission peak in the emissionspectrum of the β-sialon fluorescent material, when irradiated withlight having an excitation wavelength of 450 nm, is 50 nm or so, thatis, the half value width of the aluminate fluorescent material of thefirst embodiment of the present disclosure is narrower. The aluminatefluorescent material has a narrow half value width of the emission peakin the emission spectrum, and therefore has a high color purity. Forexample, when the light emitting device including the aluminatefluorescent material is used as a backlight for liquid crystals, thecolor reproducibility range can be broadened.

The aluminate fluorescent material of the first embodiment of thepresent disclosure is activated by manganese (Mn) and emits green lightthrough photoexcitation in a near-UV to blue region. Specifically, thealuminate fluorescent material absorbs light falling within a wavelengthrange of 380 nm to 485 nm, and the emission peak wavelength in theemission spectrum thereof falls preferably in a range of 485 nm or moreand 570 nm or less, more preferably in a range of 495 nm or more and 560nm or less, even more preferably in a range of 505 nm or more and 550 nmor less.

Light Emitting Device

One example of a light emitting device, which is the second embodimentof the present disclosure and which includes the aluminate fluorescentmaterial of the first embodiment of the present disclosure, is describedwith reference to FIG. 1. FIG. 1 is a schematic cross-sectional viewshowing an example of a light emitting device 100 of an embodiment ofthe present disclosure.

The light emitting device 100 is provided with a molded article 40, alight emitting element 10 and a fluorescent member 50. The moldedarticle 40 is integrally composed of a first lead 20, a second lead 30and a resin part 42 containing a thermoplastic resin or a thermosettingresin. The molded article 40 forms a recess part having a bottom faceand a side face, and the light emitting element 10 is mounted on thebottom face of the recess part. The light emitting element 10 has a pairof positive and negative electrodes, and the pair of positive andnegative electrodes each are individually electrically connected to thefirst lead 20 and the second lead 30 each via a wire 60. The lightemitting element 10 is covered with the fluorescent member 50. Thefluorescent member 50 contains, for example, a fluorescent material 70for wavelength conversion of the light from the light emitting element10, and a resin. Further, the fluorescent material 70 contains a firstfluorescent material 71 and a second fluorescent material 72. The firstlead 20 and the second lead 30 connected to the pair of positive andnegative electrodes of the light emitting element 10 are partly exposedtoward the outside of the package to constitute the light emittingdevice 100. Via these first lead 20 and second lead 30, the lightemitting device 100 receives external power to emit light.

The light emitting element 10 is used as an excitation light source, andpreferably has an emission peak wavelength within a range of 380 nm ormore and 485 nm or less. The range of the emission peak wavelength ofthe light emitting element 10 is preferably in a range of 390 nm or moreand 480 nm or less, more preferably in a range of 420 nm or more and 470nm or less. The aluminate fluorescent material of the first embodimentof the present disclosure is efficiently excited by the excitation lightsource having an emission spectrum within a range of 380 nm or more and485 nm or less. Regarding the aluminate fluorescent material, inparticular, the optical reflectance thereof from an excitation lightsource having an emission peak wavelength within a range of 420 nm ormore and 470 nm or less is low, that is, the light absorptivity thereofis high and the aluminate fluorescent material can be efficientlyexcited by the light. The aluminate fluorescent material of the firstembodiment of the present disclosure can be efficiently excited by thelight from the excitation light source having an emission peakwavelength within the above-mentioned wavelength range, and using thealuminate fluorescent material having such a high emission intensity ofthe type, the light emitting device 100 that can emit mixed light of thelight from the light emitting element 10 and the fluorescence from thefluorescent material 70 can be constructed.

The half value width of the emission spectrum of the light emittingelement 10 is, for example, 30 nm or less.

Preferably, the light emitting element 10 uses a semiconductor lightemitting element. Using the semiconductor light emitting element as alight source, a stable light emitting device having a high efficiencyand a high linearity of output to input and having high mechanicalimpact resistance can be obtained.

Examples of the semiconductor light emitting element include asemiconductor light emitting element using a nitride semiconductor(In_(X)Al_(Y)Ga_(1−X−Y)N, 0≤X, 0≤Y, X+Y≤1).

The light emitting device 100 includes at least the aluminatefluorescent material of the first embodiment of the present disclosure,and preferably contains the aluminate fluorescent material having acomposition represented by the formula (I).

The first fluorescent material 71 containing the aluminate fluorescentmaterial of the first embodiment of the present disclosure can becontained, for example, in the fluorescent member 50 to cover the lightemitting element 10, thereby constituting the light emitting device 100.In the light emitting device 100 in which the light emitting element 10is covered by the fluorescent member 50 that contains the firstfluorescent material 71 including the aluminate fluorescent material, apart of the light released from the light emitting element 10 isabsorbed by the aluminate fluorescent material and is thereby emitted asgreen light. Using the light emitting element 10 that emits light havingan emission spectrum within a wavelength in a range of 380 nm or moreand 485 nm or less, especially emitting light having an emissionspectrum within a wavelength in a range of 420 nm or more and 470 nm orless, the emitted light can be more effectively utilized. Accordingly, alight emitting device having a high emission efficiency can be provided.

The content of the first fluorescent material 71 is, for example, in arange of 1 part by mass or more and 50 parts by mass or less relative tothe resin (100 parts by mass) and is preferably in a range of 2 parts bymass or more and 40 parts by mass or less.

Preferably, the fluorescent member 50 contains the second fluorescentmaterial 72 whose emission peak wavelength differs from that of thefirst fluorescent material 71. For example, the light emitting device100 is provided with the light emitting element 10 having an emissionspectrum within a wavelength range of 380 nm or more and 485 nm or less,and especially emitting light having an emission peak wavelength withina range of 420 nm or more and 470 nm or less, and the first fluorescentmaterial 71 containing the aluminate fluorescent material of the firstembodiment of the present disclosure that is excited by the light, andoptionally the second fluorescent material 72, and consequently, thelight emitting device 100 can have a broad color reproducibility rangeand good color rendering properties.

The second fluorescent material 72 may be any one that absorbs lightfrom the light emitting element 10 for wavelength conversion into lighthaving a different wavelength of the first fluorescent material 71.Examples thereof include (Ca,Sr,Ba)₂SiO₄:Eu, (Y,Gd,Lu)₃(Ga,Al)₅O₁₂:Ce,(Si,Al)₆(O,N)₈:Eu, SrGa₂S₄:Eu, K₂SiF₆:Mn, (Ba,Ca,Sr)₂Si₅N₈:Eu,CaAlSiN₃:Eu, (Ca,Sr)AlSiN₃:Eu, (Ca,Sr,Ba)₈MgSi₄O₁₆(F,Cl,Br)₂:Eu,(Y,La)₃Si₆N₁₁:Ce, Ca₃Sc₂Si₃O₁₂:Ce, CaSc₄O₄:Ce, etc.

In the case where the fluorescent member 50 further contains the secondfluorescent material 72, the second fluorescent material 72 ispreferably a red fluorescent material to emit a red color, andpreferably absorbs light falling within a wavelength range of 380 nm ormore and 485 nm or less, and emits light falling within a wavelength ina range of 610 nm or more and 780 nm or less. Containing the redfluorescent material, the light emitting device can be more favorablyapplied to lighting systems, liquid crystal display devices, etc.

The red fluorescent material includes a tetravalent Mn-activatedfluoride fluorescent material having a compositional formula representedby K₂SiF₆:Mn, a divalent Eu-activated nitride fluorescent materialrepresented by CaSiAlN₃:Eu, (Ca,Sr)AlSiN₃:Eu, SrLiAl₃N₄:Eu, etc. Amongthese, the red fluorescent material is, from the viewpoint of increasingthe color purity and broadening the color reproducibility range,preferably a tetravalent Mn-activated fluoride fluorescent material ofsuch that the half value width of the emission spectrum thereof is 20 nmor less.

The first fluorescent material 71 and the second fluorescent material 72(the two may be simply referred to as “fluorescent material 70” ascombined), along with a sealant material, constitute the fluorescentmember 50 that covers the light emitting element 10. The sealantmaterial to constitute the fluorescent member 50 includes a siliconeresin, an epoxy resin, etc.

The total content of the fluorescent material 70 in the fluorescentmember 50 may be, for example, in a range of 5 parts by mass or more and300 parts by mass or less, relative to the resin (100 parts by mass),and is preferably in a range of 10 parts by mass or more and 250 partsby mass or less, even more preferably in a range of 15 parts by mass ormore and 230 parts by mass or less, still more preferably in a range of15 parts by mass or more and 200 parts by mass or less. When the totalcontent of the fluorescent material 70 in the fluorescent member 50falls within the range, the light emitted by the light emitting element10 can be efficiently processed for wavelength conversion by thefluorescent material 70.

The fluorescent member 50 may further contain a filler, a light diffuserand the like in addition to the sealant material and the fluorescentmaterial 70. For example, containing a light diffuser, the member canrelieve the directionality from the light emitting element 10 and cantherefore enlarge the viewing angle. Examples of the filler includesilica, titanium oxide, zinc oxide, zirconium oxide, alumina, etc. Inthe case where the fluorescent member 50 contains a filler, the fillercontent may be, for example, in a range of 1 part by mass or more and 20parts by mass or less relative to the resin (100 parts by mass).

Method of Producing an Aluminate Fluorescent Material

Next, as the third embodiment of the present disclosure, a method ofproducing the aluminate fluorescent material of the first embodiment ofthe present disclosure is described. The aluminate fluorescent materialcan be produced using compounds containing elements that constitute thecomposition of the aluminate fluorescent material.

Compound Containing Elements to Constitute Composition of AluminateFluorescent Material

The compounds containing elements to constitute the composition of thealuminate fluorescent material include compounds containing aluminum(Al), compounds containing barium (Ba), optionally compounds containingstrontium (Sr), compounds containing magnesium (Mg), and compoundscontaining manganese (Mn).

Aluminum-Containing Compounds

The aluminum-containing compounds include Al-containing oxides,hydroxides, nitrides, oxynitrides, fluorides, chlorides, etc. Thesecompounds may be hydrates. As the aluminum-containing compound, analuminum metal elementary substance or an aluminum alloy may also beused or the metal elementary substance or the alloy may be used for atleast a part of the compounds to be used.

Specific examples of the Al-containing compounds include Al₂O₃, Al(OH)₃,AlN, AlON, AlF₃, AlCl₃, etc. One alone or two or more kinds of theAl-containing compounds may be used either singly or combined. TheAl-containing compound is preferably an oxide (Al₂O₃). As compared withany other material, the oxide does not contain any other element thanthose of the intended composition of the aluminate fluorescent material,and can readily give the fluorescent material having a desiredcomposition. In addition, in the case where a compound having any otherelement than those to be the intended composition is used, residualimpurity elements may remain in the resultant fluorescent material, andthe residual impurity elements may be killer factors against lightemission and the emission intensity would be thereby noticeably lowered.

Barium-Containing Compound

The barium-containing compounds include Ba-containing oxides,hydroxides, carbonates, nitrates, sulfates, carboxylates, halides,nitrides, etc. These barium-containing compounds may be in the form ofhydrates. Specific examples thereof include BaO, Ba(OH)₂.8H₂O, BaCO₃,Ba(NO₃)₂, BaSO₄, Ba(OCOH)₂.2H₂O, Ba(OCOCH₃)₂, BaCl₂.6H₂O, Ba₃N₂, BaNH,etc. One alone or two or more kinds of the Ba-containing compounds maybe used either singly or as combined. Among these, from the viewpoint ofeasiness in handling, carbonates and oxides are preferred. ABa-containing carbonate (BaCO₃) is more preferred as it is stable inair, it can readily decompose by heating, any other element than thoseof the intended composition hardly remain, and it is easy to preventemission intensity reduction owing to residual impurity elements.

Strontium-Containing Compound

The strontium-containing compounds include Sr containing oxides,hydroxides, carbonates, nitrates, sulfates, carboxylates, halides,nitrides, etc. These strontium-containing compounds may be in the formof hydrates. Specific examples thereof include SrO, Sr(OH)₂.8H₂O, SrCO₃,Sr(NO₃)₂.4H₂O, SrSO₄, Sr(OCOH)₂.H₂O, Sr(OCOCH₃)₂.0.5H₂O, SrCl₂.6H₂O,Sr₃N₂, SrNH, etc. One alone or two or more kinds of the Sr-containingcompounds may be used either singly or as combined. Among these, fromthe viewpoint of easiness in handling, carbonates and oxides arepreferred. A Sr-containing carbonate (SrCO₃) is more preferred as it isstable in air, it can readily decompose by heating, any other elementthan those of the intended composition hardly remain, and it is easy toprevent emission intensity reduction owing to residual impurityelements.

Magnesium-Containing Compounds

The magnesium-containing compounds include Mg-containing oxides,hydroxides, carbonates, nitrates, sulfates, carboxylates, halides,nitrides, etc. These magnesium-containing compounds may be in the formof hydrates. Specific examples thereof include MgO, Mg(OH)₂,3MgCO₃.Mg(OH)₂.3H₂O, MgCO₃.Mg(OH)₂.2H₂O, Mg(NO₃)₂.6H₂O, MgSO₄,Mg(OCOH)₂.H₂O, Mg(OCOCH₃)₂.4H₂O, MgCl₂, Mg₃N₂, MgNH, etc. One alone ortwo or more kinds of the Mg-containing compounds may be used eithersingly or as combined. Among these, from the viewpoint of easiness inhandling, carbonates and oxides are preferred. A Mg-containing oxide(MgO) is more preferred as it is stable in air, it can readily decomposeby heating, any other element than those of the intended compositionhardly remain, and it is easy to prevent emission intensity reductionowing to residual impurity elements.

Manganese-Containing Compound

The manganese-containing compounds include Mn-containing oxides,hydroxides, carbonates, nitrates, sulfates, carboxylates, halides,nitrides, etc. These manganese-containing compounds may be in the formof hydrates. Specific examples thereof include MnO₂, Mn₂O₃, Mn₃O₄, MnO,Mn(OH)₂, MnCO₃, Mn(NO₃)₂, Mn(OCOCH₃)₂.2H₂O, Mn(OCOCH₃)₃.2H₂O,MnCl₂.4H₂O, etc. One alone or two or more kinds of the Mn-containingcompounds may be used either singly or as combined. Among these, fromthe viewpoint of easiness in handling, carbonates and oxides arepreferred. A Mn-containing carbonate (MnCO₃) is more preferred as it isstable in air, it can readily decompose by heating, any other elementthan those of the intended composition hardly remain, and it is easy toprevent emission intensity reduction owing to residual impurityelements.

Mixing of Compounds

In the method of producing the aluminate fluorescent material of thethird embodiment of the present disclosure, at least one or more kindsof compounds selected from Ba-containing compounds and Sr-containingcompounds, a Mg-containing compound, a Mn-containing compound, and anAl-containing compounds are mixed in such a manner that the aluminatefluorescent material to be produced could have a composition where themolar ratio of Al is taken as 10, the total molar ratio of the firstelement containing one or more elements selected from Ba and Sr is avalue of a parameter a, the total molar ratio of the second elementcontaining Mg and Mn is a value of a parameter b, the molar ratio of Sris a product of a value of a parameter m and the value of the parametera, the molar ratio of Mn is a product of a value of a parameter n andthe value of the parameter b, the values of the parameters a and b arevalues satisfying the following requirement (1), the value of theparameter m is a value satisfying the following requirement (2), and thevalue of the parameter n is a value satisfying the following requirement(3), thereby preparing a raw material mixture.0.5<b<a≤0.5b+0.5<1.0  (1)0≤m≤1.0  (2)0.4≤n≤0.7  (3)

Preferably, the element-containing compounds are mixed in such a mannerthat the values of the parameters a and b could be values satisfying thefollowing requirement (4).0.7<b<a≤0.5b+0.5<1.0  (4)

When the value of the parameter b is larger than 0.7 and when the valueof the parameters a and b are numbers satisfying the above requirement(4), the crystal structure of the aluminate fluorescent material can bestable and the emitting intensity of the resultant aluminate fluorescentmaterial can be high.

Preferably, the value of the parameter n satisfies a requirement of0.4≤n≤0.6, or the product of the value of the parameter b and the valueof the parameter n (b×n) is a value satisfying a requirement of0.3<b×n<0.6.

Accordingly, the Mn activation amount can fall within an optimum range,and light absorption in a near-UV to blue region contained in theexcitation light source can be promoted, and consequently, concentrationquenching to be caused by too much Mn activation can be prevented, theemission intensity can be increased, and the emission intensity throughphotoexcitation in a near UV to blue region can be further increased.

The raw material mixture may optionally contain a flux of halide or thelike. In the raw material mixture containing a flux, reaction betweenthe raw materials can be promoted and solid-phase reaction can go onmore uniformly. This is because the temperature of heat treatment forthe raw material mixture would be nearly the same as the liquid phaseformation temperature for halides and the like to be used as the flux,or would be higher than the liquid phase formation temperature, andtherefore the reaction could be promoted.

The halides includes fluorides, chlorides and others of rare earthmetals, alkaline earth metals, alkali metals, etc. In the case where analkaline earth metal halide is used as the flux, the flux may be addedas the compound to provide the composition of the intended aluminatefluorescent material. Specific examples of the flux include bariumfluoride (BaF₂), strontium fluoride (SrF₂), magnesium fluoride (MgF₂),aluminum fluoride (AlF₃), manganese fluoride (MnF₂), calcium fluoride(CaF₂), etc. Magnesium fluoride (MgF₂) is preferred. This is because, byusing magnesium fluoride as the flux, the crystal structure isstabilized.

In the case where the raw material mixture contains the flux, the fluxcontent is preferably 10% by mass or less, based on the raw materialmixture (100% by mass), more preferably 5% by mass or less, and ispreferably 0.1% by mass or more. When the flux content falls within therange, difficulty in formation of crystal structure owing to shortage ofthe flux to cause grain growth failure could be evaded, and difficultyin formation of crystal structure owing to excessive flux could also beevaded.

For the raw material mixture, the compounds each containing the intendedelement are weighed to be in a desired blending ratio, and then groundand mixed using, for example, a dry-process grinding machine such as aball mill, a shaking mill, a hammer mill, a roll mill, a jet mill, ormay be ground and mixed using a mortar and a pestle, etc. For example,the compounds may be mixed using a mixing machine such as a ribbonblender, a Henschel mixer, a V-shaped blender, or may be ground andmixed using both the dry-process grind machine and the mixing machine.The mixing may be dry-process mixing, or may also be wet-process mixingwith a solvent added to the system. Dry-process mixing is preferred.This is because the processing time may be shortened more in dry-processmixing than in wet-process mixing, therefore leading to productivityimprovement.

Heat Treatment of Raw Material Mixture

The raw material mixture may be heat-treated in a crucible, a boatformed of a carbonaceous material such as graphite or the like, or amaterial of boron nitride (BN), aluminum oxide (alumina), tungsten (W),molybdenum (Mo), etc.

The heat treatment temperature for the raw material mixture is, from theviewpoint of the stability of the crystal structure, preferably in arange of 1,000° C. or higher and 1,800° C. or lower, more preferably ina range of 1,100° C. or higher and 1,750° C. or lower, even morepreferably in a range of 1,200° C. or higher and 1,700° C. or lower,especially more preferably in a range of 1,300° C. or higher and 1,650°C. or lower.

The heat treatment time differs depending on the heating speed, the heattreatment atmosphere and others. After the system has reached the heattreatment temperature, it is kept as such preferably for 1 hour or more,more preferably 2 hours or more, even more preferably 3 hours or more,and preferably 20 hours or less, more preferably 18 hours or less, evenmore preferably 15 hours or less.

The atmosphere for heat treatment for the raw material mixture may be aninert atmosphere of argon, nitrogen, a reductive atmosphere containinghydrogen, or an oxidative atmosphere such as air, etc. Preferably, theraw material mixture is heat-treated in a reductive nitrogen atmosphereto give a fluorescent material. More preferably, the atmosphere for heattreatment for the raw material mixture is a nitrogen atmospherecontaining a reductive hydrogen gas.

For the aluminate fluorescent material, the raw material mixture can bemore reactive in an atmosphere having a high reductive power such as areductive atmosphere containing hydrogen and nitrogen, and can beheat-treated therein under an atmospheric pressure withoutpressurization. For the heat treatment, for example, an electricfurnace, a gas furnace or the like may be used.

Post Treatment

The resultant fluorescent material may be post-treated for wetdispersion, wet-process sieving, dewatering, drying, dry-processsieving. According to such post treatment, a fluorescent material havinga desired mean particle size can be obtained. For example, thefluorescent material after post treatment is dispersed in a solvent,then the dispersed fluorescent material is put on a sieve, and while asolvent flow is given thereto along with various shaking given theretovia the sieve, the baked product is led to pass through a mesh forwet-process sieving, and then dewatered, dried and dry-sieved to give afluorescent material having a desired mean particle size.

By dispersing the fluorescent material after heat treatment in a medium,impurities such as baked residues of flux as well as unreactedcomponents of the raw materials can be removed. For wet-processdispersing, dispersion media such as alumina balls, zirconia balls, andthe like may be used.

EXAMPLES

The present invention is hereunder specifically described by referenceto the following Examples and Comparative Examples.

Example 1

As raw materials, 36.6 g of BaCO₃ (BaCO₃ content: 99.3 mass %), 27.4 gof SrCO₃ (SrCO₃ content: 99.0 mass %), 204.9 g of Al₂O₃ (Al₂O₃ content:99.5 mass %), 4.0 g of MgO (MgO content: 98.0 mass %), 24.7 g of MnCO₃(MnCO₃ content: 94.8 mass %) were weighed so that the blending molarratio could have a composition represented by(Ba_(0.5)Sr_(0.5))_(0.92)(Mg_(0.4)Mn_(0.6))_(0.85)Al₁₀O_(16.77), and asa flux, 2.5 g of MgF₂ was added and dry-blended to give a raw materialmixture. The resultant raw material mixture was filled in an aluminacrucible and the crucible was closed with a lid, and in a mixedatmosphere of 3 vol % of H₂ and 97 vol % of N₂, heat treatment wasperformed at 1,500° C. for 5 hours to give an aluminate fluorescentmaterial.

Example 2

An aluminate fluorescent material was obtained in the same manner as inExample 1 except that, as raw material, 37.8 g of BaCO₃, 28.4 g ofSrCO₃, 205.6 g of Al₂O₃, 7.6 g of MgO and 18.1 g of MnCO₃ were weighedso that the blending molar ratio could have a composition represented by(Ba_(0.5)Sr_(0.5))_(0.95)(Mg_(0.6)Mn_(0.4))_(0.93)Al₁₀O_(16.88), and asa flux, 2.5 g of MgF₂ was added.

Example 3

An aluminate fluorescent material was obtained in the same manner as inExample 1 except that, as raw material, 37.1 g of BaCO₃, 27.8 g ofSrCO₃, 201.6 g of Al₂O₃, 4.4 g of MgO and 26.6 g of MnCO₃ were weighedso that the blending molar ratio could have a composition represented by(Ba_(0.5)Sr_(0.5))_(0.95)(Mg_(0.4)Mn_(0.6))_(0.93)Al₁₀O_(16.88), and asa flux, 2.5 g of MgF₂ was added.

Example 4

An aluminate fluorescent material was obtained in the same manner as inExample 1 except that, as raw material, 37.2 g of BaCO₃, 27.9 g ofSrCO₃, 208.6 g of Al₂O₃, 6.9 g of MgO and 16.8 g of MnCO₃ were weighedso that the blending molar ratio could have a composition represented by(Ba_(0.5)Sr_(0.5))_(0.92)(Mg_(0.6)Mn_(0.4))_(0.85)Al₁₀O_(16.77), and asa flux, 2.5 g of MgF₂ was added.

Example 5

An aluminate fluorescent material was obtained in the same manner as inExample 1 except that, as raw material, 36.2 g of BaCO₃, 27.2 g ofSrCO₃, 203.0 g of Al₂O₃, 2.5 g of MgO and 28.6 g of MnCO₃ were weighedso that the blending molar ratio could have a composition represented by(Ba_(0.5)Sr_(0.5))_(0.92)(Mg_(0.3)Mn_(0.7))_(0.85)Al₁₀O_(16.77), and asa flux, 2.5 g of MgF₂ was added.

Comparative Example 1

An aluminate fluorescent material was obtained in the same manner as inExample 1 except that, as raw material, 38.6 g of BaCO₃, 29.0 g ofSrCO₃, 209.8 g of Al₂O₃, 10.9 g of MgO and 9.2 g of MnCO₃ were weighedso that the blending molar ratio could have a composition represented by(Ba_(0.5)Sr_(0.5))_(0.95)(Mg_(0.8)Mn_(0.2))_(0.93)Al₁₀O_(16.88), and asa flux, 2.5 g of MgF₂ was added.

Comparative Example 2

An aluminate fluorescent material was obtained in the same manner as inExample 1 except that, as raw material, 38.3 g of BaCO₃, 28.8 g ofSrCO₃, 197.7 g of Al₂O₃, 4.8 g of MgO and 28.1 g of MnCO₃ were weighedso that the blending molar ratio could have a composition represented by(Ba_(0.5)Sr_(0.5))_(1.00)(Mg_(0.4)Mn_(0.6))_(1.00)Al₁₀O_(17.00), and asa flux, 2.4 g of MgF₂ was added.

Comparative Example 3

An aluminate fluorescent material was obtained in the same manner as inExample 1 except that, as raw material, 36.4 g of BaCO₃, 27.3 g ofSrCO₃, 197.8 g of Al₂O₃, 1.4 g of MgO and 34.8 g of MnCO₃ were weighedso that the blending molar ratio could have a composition represented by(Ba_(0.5)Sr_(0.5))_(0.95)(Mg_(0.2)Mn_(0.8))_(0.93)Al₁₀O_(16.88), and asa flux, 2.4 g of MgF₂ was added.

Evaluation of Emission Characteristics

Relative Emission Intensity (%)

The emission characteristics of the fluorescent materials of Examplesand Comparative Examples were measured. Using a quantum efficiencymeasurement system (QE-2000 manufactured by Otsuka Electronics Co.,Ltd.), each fluorescent material was irradiated with light having anexcitation wavelength of 450 nm to measure the emission spectrum thereofat room temperature (25° C.±5° C.). The emission intensity (%) of theresultant emission spectrum was determined. The relative emissionintensity was calculated based on the emission intensity 100% of thefluorescent material of Comparative Example 1. The results are shown inTable 1. FIG. 2 shows the emission spectrum of the relative emissionintensity (%) to wavelength of the aluminate fluorescent materials ofExample 1 and Comparative Example 1.

Half Value Width: FWHM

The half value width (FWHM) of the resultant emission spectrum of thefluorescent material of Examples and Comparative Examples was measured.The results are shown in Table 1.

Emission Peak Wavelength

The wavelength at which the resultant emission spectrum of thefluorescent material of each of the Examples and Comparative Exampleswas at a maximum was determined as an emission peak wavelength (nm). Theresults are shown in Table 1.

Reflectance (%)

Using a spectral fluorophotometer (F-4500 manufactured by HitachiHigh-technologies Corporation), a sample of the fluorescent material ofExamples and Comparative Examples was irradiated with light from anexcitation light source, halogen lamp at room temperature (25° C.±5°C.), and the wavelength of the spectroscope on the excitation side andthe fluorescence side was scanned as combined to measure the reflectedlight. The proportion of the reflected light relative to the lighthaving an excitation wavelength of 450 nm is shown in Table 1 as areflectance (%) based on the reflectance of CaHPO₄. In addition, thereflectance to wavelength of the fluorescent material of Example 1 andthe fluorescent material of Comparative Example 1 is shown in FIG. 3 asa reflection spectrum thereof.

TABLE 1 Optical Characteristics Relative Emission Emission Peak 450 nmIntensity Wavelength FWHM Reflectance Compositional Ratio a b m n b × n(%) (nm) (nm) (%) Example 1(Ba_(0.5)Sr_(0.5))_(0.92)(Mg_(0.4)Mn_(0.6))_(0.85)Al₁₀O_(16.77) 0.920.85 0.5 0.6 0.510 152 518 29 78.3 Example 2(Ba_(0.5)Sr_(0.5))_(0.95)(Mg_(0.6)Mn_(0.4))_(0.93)Al₁₀O_(16.88) 0.950.93 0.5 0.4 0.372 141 517 28 79.9 Example 3(Ba_(0.5)Sr_(0.5))_(0.95)(Mg_(0.4)Mn_(0.6))_(0.93)Al₁₀O_(16.88) 0.950.93 0.5 0.6 0.558 135 518 29 76.6 Example 4(Ba_(0.5)Sr_(0.5))_(0.92)(Mg_(0.6)Mn_(0.4))_(0.85)Al₁₀O_(16.77) 0.920.85 0.5 0.4 0.340 135 517 29 79.8 Example 5(Ba_(0.5)Sr_(0.5))_(0.92)(Mg_(0.3)Mn_(0.7))_(0.85)Al₁₀O_(16.77) 0.920.85 0.5 0.7 0.595 111 517 29 76.9 Comparative(Ba_(0.5)Sr_(0.5))_(0.95)(Mg_(0.8)Mn_(0.2))_(0.93)Al₁₀O_(16.88) 0.950.93 0.5 0.2 0.186 100 516 28 86.9 Example 1 Comparative(Ba_(0.5)Sr_(0.5))_(1.00)(Mg_(0.4)Mn_(0.6))_(1.00)Al₁₀O_(17.00) 1.001.00 0.5 0.6 0.600 84 517 29 75.6 Example 2 Comparative(Ba_(0.5)Sr_(0.5))_(0.95)(Mg_(0.2)Mn_(0.8))_(0.93)Al₁₀O_(16.88) 0.950.93 0.5 0.8 0.744 13 518 29 75.2 Example 3

As shown in Table 1, in the compositions of the aluminate fluorescentmaterials of Examples 1 to 5, the value of the parameters a, b, m and nsatisfies the requirements (1) to (3) when the molar ratio Al is takenas 10. The aluminate fluorescent materials of these Examples 1 to 5 hada higher relative emission intensity owing to excitation of blue lighthaving an emission peak wavelength of 450 nm, than those of ComparativeExamples 1 to 3. In particular, in the aluminate fluorescent materialsof Examples 1 to 4, the value of the parameter n indicating the molarratio of Mn in the second element (Mg and Mn) satisfies 0.4≤n≤0.6, andthe product of the value of the parameter n indicating the molar ratioof Mn and the value of the parameter b (b×n) satisfies the requirementof 0.3<b×n<0.6, when the molar ratio Al is taken as 10, and thereforethe relative emission intensity of the aluminate fluorescent materialswas 135% or more and was extremely high owing to excitation of bluelight having an emission peak wavelength of 450 nm. In addition, as alsoshown in Table 1, the reflectance of the aluminate fluorescent materialsof Examples 1 to 5 to the excitation light, blue light having anemission peak wavelength of 450 nm was 80% or less and was low. Fromthese results, it is confirmed that the aluminate fluorescent materialsof Examples 1 to 5 greatly absorb a part of the excitation light, bluelight having an emission peak wavelength of 450 nm, and emitsfluorescence at a high emission intensity.

As shown in Table 1, in the composition of the aluminate fluorescentmaterial of Comparative Example 1, the value of the parameter nindicating the molar ratio of Mn in the second element (Mg and Mn) didnot satisfy the requirement (3), 0.4≤n≤0.7. In Comparative Example 1,the reflectance was more than 80%, and was higher than the reflectanceof the aluminate fluorescent materials of Examples 1 to 5, in otherwords, the absorbance of the excitation light having an emission peakwavelength of 450 nm of the former was small and the relative emissionintensity of the former was lower than that of the aluminate fluorescentmaterials of Examples 1 to 5.

Also as shown in Table 1, in the composition of the aluminatefluorescent material of Comparative Example 2, the value of theparameter a indicating the total molar ratio of the first element (Ba,Sr) was equal to the value of the parameter b indicating the total molarratio of the second element (Mg and Mn), and did not satisfy therequirement (1). In Comparative Example 2, the relative emissionintensity was low.

Also as shown in Table 1, in the composition of the aluminatefluorescent material of Comparative Example 3, the value of theparameter n indicating the molar ratio of Mn in the second element (Mgand Mn) did not satisfy the requirement (3), 0.4≤n≤0.7, and the value ofthe parameter n was larger than the upper limit, 0.7. In ComparativeExample 3, the relative emission intensity was 13% and was extremelylow.

In the compositions of the aluminate fluorescent materials ofComparative Examples 1 to 3, the product of the value of the parameter nindicating the molar ratio of Mn and the value of the parameter b (b×n)did not satisfy the requirement of 0.3<b×n<0.6.

In addition, as shown in Table 1, the half value width of the emissionpeak in the emission spectrum of the aluminate fluorescent materials ofExamples 1 to 5 was less than 30 nm and was narrow.

As shown in Table 1 and FIG. 2, the aluminate fluorescent materials ofExamples 1 to 5 emitted light whose emission peak wavelength fallswithin a range of 516 nm to 518 nm, through excitation of blue lighthaving an emission peak intensity of 450 nm. As shown in the emissionspectrum in FIG. 2, the relative emission intensity at the emission peakwavelength of the aluminate fluorescent material of Example 1 was higherthan the relative emission intensity of Comparative Example 1.

Also as shown in FIG. 3, the reflection spectrum within a range of 420nm or more and 470 nm or less of the aluminate fluorescent material ofExample 1 was lower than the reflection spectrum within the same rangeof the aluminate fluorescent material of Comparative Example 1, and inparticular, the absorption of excitation light having a wavelength of420 nm or more and 470 nm or less of the former is high, and it isconfirmed that the aluminate fluorescent material of Example 1 absorbedthe excitation light falling within the wavelength range and emittedfluorescence at a high emission intensity.

In accordance with an embodiment of the present invention, it ispossible to provide an aluminate fluorescent material having a highemission intensity as a green emitting fluorescent material that isexcited with light falling in a near-UV to blue region. The lightemitting device using the aluminate fluorescent material can be used ina wide range of fields of general lighting, in-car lighting, displays,backlights for liquid crystals, traffic lights, lighting switches, etc.The aluminate fluorescent material of one embodiment of the presentdisclosure has a high emission intensity, has a narrow half value widthof an emission peak and has a high color purity, and therefore canbroaden the color reproducibility range, and is favorably usable as abacklight source for liquid crystals.

Although the present disclosure has been described with reference toseveral exemplary embodiments, it shall be understood that the wordsthat have been used are words of description and illustration, ratherthan words of limitation. Changes may be made within the purview of theappended claims, as presently stated and as amended, without departingfrom the scope and spirit of the disclosure in its aspects. Although thedisclosure has been described with reference to particular examples,means, and embodiments, the disclosure may be not intended to be limitedto the particulars disclosed; rather the disclosure extends to allfunctionally equivalent structures, methods, and uses such as are withinthe scope of the appended claims.

One or more examples or embodiments of the disclosure may be referred toherein, individually and/or collectively, by the term “disclosure”merely for convenience and without intending to voluntarily limit thescope of this application to any particular disclosure or inventiveconcept. Moreover, although specific examples and embodiments have beenillustrated and described herein, it should be appreciated that anysubsequent arrangement designed to achieve the same or similar purposemay be substituted for the specific examples or embodiments shown. Thisdisclosure may be intended to cover any and all subsequent adaptationsor variations of various examples and embodiments. Combinations of theabove examples and embodiments, and other examples and embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the description.

In addition, in the foregoing Detailed Description, various features maybe grouped together or described in a single embodiment for the purposeof streamlining the disclosure. This disclosure may be not to beinterpreted as reflecting an intention that the claimed embodimentsrequire more features than are expressly recited in each claim. Rather,as the following claims reflect, inventive subject matter may bedirected to less than all of the features of any of the disclosedembodiments. Thus, the following claims are incorporated into theDetailed Description, with each claim standing on its own as definingseparately claimed subject matter.

The above disclosed subject matter shall be considered illustrative, andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments which fall within thetrue spirit and scope of the present disclosure. Thus, to the maximumextent allowed by law, the scope of the present disclosure may bedetermined by the broadest permissible interpretation of the followingclaims and their equivalents, and shall not be restricted or limited bythe foregoing detailed description.

What is claimed is:
 1. A method of producing an aluminate fluorescentmaterial, comprising: mixing compounds that contain elements to providea composition containing a first element that contains one or moreelements selected from Ba and Sr, a second element that contains Mg andMn, and Al and O to obtain a raw material mixture, and heat-treating theraw material mixture, wherein: in the composition, when a molar ratio ofAl is taken as 10, a total molar ratio of the first element is a valueof a parameter a, a total molar ratio of the second element is a valueof a parameter b, a molar ratio of Sr is a product of a value of aparameter m and the value of the parameter a, a molar ratio of Mn is aproduct of a value of a parameter n and the value of the parameter b,and the values of the parameters a and b satisfy the followingrequirement (1), the value of the parameter m satisfies the followingrequirement (2), and the value of the parameter n satisfies thefollowing requirement (3):0.7<b<a≤0.5b+0.5<1.0  (1), and0≤m≤1.0  (2) wherein the value of the parameter n satisfies 0.6≤n<0.7,or the product of the value of the parameter b and the value of theparameter n (b×n) is a value satisfying 0.3<b×n<0.6.
 2. The method ofproducing an aluminate fluorescent material according to claim 1,wherein the compounds containing elements comprise a compound containingaluminum, a compound containing barium, optionally a compound containingstrontium, a compound containing magnesium, and a compound containingmanganese.
 3. The method of producing an aluminate fluorescent materialaccording to claim 2, wherein the compound containing aluminum includesan Al-containing oxide, an Al-containing hydroxide, an Al-containingnitride, an Al-containing oxynitride, an Al-containing fluoride, anAl-containing chloride, or a combination thereof.
 4. The method ofproducing an aluminate fluorescent material according to claim 3,wherein the compound containing aluminum includes Al₂O₃, Al(OH)₃, AlN,AlF₃, AlCl₃, or a combination thereof.
 5. The method of producing analuminate fluorescent material according to claim 2, wherein thecompound containing barium includes a Ba-containing oxide, aBa-containing hydroxide, a Ba-containing carbonate, a Ba-containingnitrate, a Ba-containing sulfate, a Ba-containing carboxylate, aBa-containing halide, a Ba-containing nitride, or a combination thereof.6. The method of producing an aluminate fluorescent material accordingto claim 5, wherein the compound containing barium (Ba) includes BaO,Ba(OH)₂.8H₂O, BaCO₃, Ba(NO₃)₂, BaSO₄, Ba(OCOH)₂.2H₂O, Ba(OCOCH₃)₂,BaCl₂.6H₂O, Ba₃N₂, or a combination thereof.
 7. The method of producingan aluminate fluorescent material according to claim 2, wherein thecompound containing strontium includes a Sr-containing oxide, aSr-containing hydroxide, a Sr-containing carbonate, a Sr-containingnitrate, a Sr-containing sulfate, a Sr-containing carboxylate, aSr-containing halide, a Sr-containing nitride, or a combination thereof.8. The method of producing an aluminate fluorescent material accordingto claim 7, wherein the compound containing strontium includes SrO,Sr(OH)₂.8H₂O, SrCO₃, Sr(NO₃)₂.4H₂O, SrSO₄, Sr(OCOH)₂.H₂O,Sr(OCOCH₃)₂.0.5H₂O, SrCl₂.6H₂O, Sr₃N₂, or a combination thereof.
 9. Themethod of producing an aluminate fluorescent material according to claim2, wherein the compound containing magnesium includes a Mg-containingoxide, a Mg-containing hydroxide, a Mg-containing carbonate, aMg-containing nitrate, a Mg-containing sulfate, a Mg-containingcarboxylate, a Mg-containing halide, a Mg-containing nitride, or acombination thereof.
 10. The method of producing an aluminatefluorescent material according to claim 9, wherein the compoundcontaining magnesium (Mg) includes MgO, Mg(OH)₂, 3MgCO₃.Mg(OH)₂.3H₂O,MgCO₃.Mg(OH)₂.2H₂O, Mg(NO₃)₂.6H₂O, MgSO₄, Mg(OCOH)₂.H₂O,Mg(OCOCH₃)₂.4H₂O, MgCl₂, Mg₃N₂, or a combination thereof.
 11. The methodof producing an aluminate fluorescent material according to claim 2,wherein the compound containing manganese includes a Mn-containingoxide, a Mn-containing hydroxide, a Mn-containing carbonate, aMn-containing nitrate, a Mn-containing sulfate, a Mn-containingcarboxylate, a Mn-containing halide, a Mn-containing nitride, or acombination thereof.
 12. The method of producing an aluminatefluorescent material according to claim 11, wherein the compoundcontaining manganese includes MnO₂, Mn₂O₃, Mn₃O₄, MnO, Mn(OH)₂, MnCO₃,Mn(NO₃)₂, Mn(OCOCH₃)₂.2H₂O, Mn(OCOCH₃)₃.2H₂O, MnCl₂.4H₂O, or acombination thereof.
 13. The method of producing an aluminatefluorescent material according to claim 1, wherein the raw materialmixture comprises the compounds containing elements and a flux, the fluxincludes a halide of a rare earth metal, a halide of an alkaline earthmetal, or a halide of an alkali metal.
 14. The method of producing analuminate fluorescent material according to claim 13, wherein the fluxincludes barium fluoride, strontium fluoride, magnesium fluoride,aluminum fluoride, manganese fluoride or calcium fluoride.
 15. Themethod of producing an aluminate fluorescent material according to claim13, wherein a content of the flux is 10% by mass or less, based on theraw material mixture (100% by mass).
 16. The method of producing analuminate fluorescent material according to claim 1, wherein theheat-treating of the raw material mixture is carried out at atemperature in a range of 1,000° C. or higher and 1,800° C.
 17. Themethod of producing an aluminate fluorescent material according to claim1, wherein the heat-treating of the raw material mixture is carried outin a reductive atmosphere containing hydrogen.